The major concentration in this project is the development of a stable, viable mammalian spinal cord slice preparation for neurophysiological investigation. This preparation should preserve known segmental organization and physiologically intact elements and synapses. The major advantages of this preparation include the ability to exchange consituents in the external environment in a controlled fashion and to allow careful identification of cellular processes and their investigation. Problems to be investigated include ionic dependencies of transmitter release; resting and action potentials; dendritic function; identification and characterization of mode of action of synaptic transmitters. The major animal to be investigated will be the rat, but other small laboratory animals will also be investigated. The lumbro-sacral spinal cord will be cross-sectioned in 400 micron slices and bathed in aerated physiological solutions. Standard electrophysiological techniques will be utilized. Although the mammalian spinal motoneuron is perhaps the best studied of central nervous system elements, much remains to be learned about its normal functioning. It is expected that a slice preparation will allow convenient investigation of most of the unsolved problems. Finally, all rational therapy of neuron system disorders depends on understanding of normal functioning of the nervous elements. This study may therefore have important therapeutic implications.